Method of drawing refractory wires.



A. J. LIEBMANN. METHOD OF DRAWING REFRACTORY WIRES.

APPLIGATION FILED FEB.21, 1913.

Patented Oct. 21, 1913.

STATES PATENT omen ALFRED I. LIEBMANN, OF NEW You, H. Y, ASSIGNOR 'ro NATHAN nornnrnnn, or

new YOIIK, n. Y.

METHOD OFDEAWING BEFBAGTQRY WI RES.

Specification 0t Lettrs' latent. Applioatlonfled lebruary a1, 1913. Serial 110. 749,770.

Patented Oct. 21, 1913'.

To all whom it may concern Be it known that I, Amman LIEBMANN, a citizen of the Republic of Sw1tzerland,-and a resident of New York, in the county and State of New York, have invented certain new anduseful Improvements in Methods of Drawing Refractory Wires, of which the following is a specification.

' This invention has reference to improvements in methods of drawing refractory wires.

It is'the special object of my invention to provide a novel method for drawing ex ceedingly fine wires of refractory metals which fine wires are used as incandescents in electric lamps, such as for instance tungsten wires in metallic filament lamps.

Heretofore in drawing exceedingly fine wiresof highly refractory metals such as tungsten, it was foimd that better results are obtained when aphite paste is applied to the wires as a lufiicant before saidwires enter the diamond die where they are reduced in diameter. The graphite paste was mechanically applied in various ways by means. of, rotary brushes and the like. It is evident that the graphite lubricant can not be applied by mechanical means in such uniform manner and thickness as is desirable and small lumps of graphite paste 00* our on one portion of the wire while other portions remain practically free from paste. This irregularity of a graphite coating on the wire is inherent toall mechanical methods of producing the same.

It is the purpose of the present invention to eliminate the described defects of the former mechanical methods of applying graphite lubricant to the refractory wires before they enter the diamond die. This has been primarily attained by the novel method formingthe subject matter of the present invention in which the lubricating agent, the graphite, is produced upon the passing wire during the process of drawing the some. The passing wire, before entering the diamond die, is subjected in a suit-' able bath containing carbonaceous liquids to anv electric treatment by means of which a. layer or coating of graphite is produced directly-on that portion. of the wire which passes through the bath and as the wire moves contlnuously the coating of graphite thereon 1s continuousl produced. In this manner a regular an uniform coating of 1 graphite 1s 1t enters the diamond die and in addition f thereto the thickness of the coatin graphite lubricant upon the surface 0 the 2 wire may be regulated to the highest-degree,

o tained on the: wire just before all as will be fully described hereinafter with reference to. the accompanying draw- 111%111 which:

a suitable bath, electric measuring instruments, a rheostat, a source of electricity,

suitable supports for the refractory wire, and exchangeable diamond die.

For the purpose of rendering the invention entirely clear one form of apparatus is shown diagrammatically on the drawing forming part of this application. Such apparatus com rises a vessel 0 which is partly filled with a liquid hydro-carbon 7) such as gasolene and the like. Within the liquid hydro-carbon there are two guiding supports'c, for the refractory wire passing through the liquid. Thesesupports 0, 0 are suitably secured in a side wall of the vessel a preferably in an insulating block (1 as shown in F ig- 2. To the sup orts c, 0 the line wires 6, e are connecte In the circuit, an ampere-meter f and variable resistance such as a rheostat g with a switch k. adapted at the same time to open and close the circuit, are inserted. A suitable source ofelectricity i furnishes the current.

The roll of wire j to be drawn finer is rotatable on the shaft Ir... The wire Z from the roll passes first through a loop msuitably supported on a block n. From the loop m the wire Z passes down into the bath underneath and in contact with the inner portion of the support a which is located within the bath as previously stated. The wire Z then passes horizontally over to the support 0 and from there rises in an upward direction and passes the loop m supported on the block 12 After passing the loop m the wire Z is drawn through the diamond die 0 where it is reduced in diameter. Now the reduced wire Z is wound up to form a spool 9' rotatable on the shaft 70 For convenience sake the support 0 of the diamond die 0 is shown to be directly connected with the adjoining short wall a of the vessel a by means of an intermediary piece 0 In coating refractory wires with a unlform layer of graphite before they pass through the diamond die I substantially proceed as follows: The wire Z from the spool j is first passed through the loop m around the support '0 within the bat-h, from the support 0 it is passed around the support 0 also located within the bath, then it is passed through the loop m outside of the l bath from where it is passed into the diamond die where it is reduced, then the reduced wire is wound upon the spool 1' Both spools are rotated on their shafts at the desired speeds. The spool j on which the greater length of wire is wound necessarily must rotate at a little higher speed. The portion of'the wire between the supports 0, 0 within the bath is completely submerged within the liquid hydro-carbon as is clearly seen from Fig. 1 of the drawing.

This submerged portion of the refractory wire is rendered incandescent by the heat of the electric current because it forms part of the circuit as shown. When the submerged portion of the wire between the supports 0 c is rendered incandescent the hydro-car on in contact therewith and sufficiently close by is decomposed and carbon is deposited on the wire in form of graphite as in a flashing process. As the wire is continuously passed through the bath and the portions being successively betweenthe supports 0, 0 successive portions of the wire are coated with graphite in a continuous process without interrupting the apparatus. In this manner a continuously working process is provided for coating refractory wires with. lubricating graphite. It is evident that the deposit of aphite on the wire may be made'of various thiclmess in accordance withthe amount of current passed through the same that is in accordance with higher or lower incandescence) of the electrically heated-up portion. The strength of the current, as indicated, is easily regulated by variable resistancesuch as the rheostat 9 shown in the drawing.- When the number graphite lubricant upon a certain thickness 'ofwire has once been determined then the apparatus is easily regulated without further tests by simply passing the determined number of amperes through that portion of the passing wire which is rendered incandescent. For a heavier deposit of graphite lubricant a, stronger current is employed while for a thinner deposit a weaker current is used. The thickness of the deposit may further be regulated to a certain extent by the speed with which the wire is drawn through the apparatus. If a certain section of the wire is rendcredincandescent for a longer time with a given current then the thickness of the coating is accordingly thickerwhile a shorter period of incandes- "cence of said section of the wire results in a thinner coating; For convenience sake a relatively thin wire is shown on the drawing but any size of wire or rod within the practical limits may likewise be treated.

I claim as my invention:

1. The mthod of drawing refractory wires consisting in passing the refractory wire to be .drawn thinner through a bath composed of a liquid hydro-carbon, rendering part of the passing wire incandescent within said hydro-carbon bath, decomposing thereby some hydro-carbon, depositing carbon on the surface of the incandescent section of the wire in form of graphite, and drawing the coated wire through a diamond die.

2. The method of drawing out tungsten wires or rods consisting in passing the tung sten wire to be drawn thinner through a bath composed of gasolene, rendering a portion of the passing wire incandescent within said gasolene bath, decomposing thereby some gasolene, depositing carbon on the surface of the incandescent tungsten wire in form of graphite, and drawing the coated tungsten wire through a diamond die.

3. The method of drawing out tungsten wires or rods consisting in passing the wire through a bath, making a portion of the wire within the bath part of an electric circuit and rendering said portion incandescent, depositing carbon on the surface of said wire portion in form ofgraphite, regulating the strength' of the current as to the required thickness of. the graphite coating, and drawing the coated wire through a diamond die, all in one continuous operation.

4. The method of coating a refractory wire to be drawn thinner with a graphite lubricant consisting in making a portion of the moving wire a part of an electric circuit while in a hydro-carbon bath and rendering said portion continuously incandescent, anddepositing thereby carbon on the incandescent surface of the passing wire in form of graphite.

' 5. The method of coating a refractory 5 said portion continuously incandescent, de-

wire to be drawn thinnerwith a graphite current according to the required thickness lubricant consisting in making a portion of of said coatin 10 the moving wire a part of an electric circuit Signed at ew York, N. Y. this 18th while in a. hydro-carbon bath and rendering day of F ebruar 1913.

. A FRED J. LIEBMANN. positing thereby carbon on the incandescent Witnesses: surface of the passing wire in form of N. Hornmm,

graphite, and regulating the strength of the ALEX. DONEGAN. 

